Letoff for looms



July 4, 1950 w. HAMILTON LET-OFF FOR LOOMS 3 Sheets-Sheet 1 Filed Nov. 21, 1946 T fi N- N Q2 2 m2 mm mw o o m I Om QNN. qwmmw @Q h Wm wm mm NH 3 Q on INVENTOR.

N m u. a A L N W AGENT July 4, 1950 w, HAMILTON 2,513,561

LET- OFF FOR LOOMS Filed Nov. 21, 1946 3 Sheets-Sheet 2 15 n ll M- U 20 11 16 I 26 I. "my M l2 l 1 11 l i ;l f;

I N VEN TOR WALLACE HAMILTON July 4, 1950 w. HAMILTON 2,513,561

LET-OFF FOR LOOMS Filed Nov. 21, 1946 3 Sheets-Sheet 3 IN VEN TOR. WALLACE HAMILTON BY g AGE VT Patented July 4, 1950 LETOFF FOR LOOMS Wallace Hamilton, Albany, N. Y., assignor to Draper Corporation, Hopedale, Mass., a corporation of Maine Application November 21, 1946, Serial No. 711,403

7 Claims.

The present invention relates generally to letofi mechanisms for looms and, as illustrated herein, relates more particularly to a positive type of let-01f mechanism wherein the warp beam is positively rotated to supply warp and wherein the let-off mechanism may be oscillated to provide for uniform warp tension.

Let-oh mechanisms of the type above referred to usually comprise a warp beam geared to a transmitting shaft which carries a pinion driven from suitable mechanism connected to the loom and acts thereby to transmit the required movement of rotation to the warp beam. The warp beam is usually operated with a step-by-step forward motion to let ofi the warp. The rate of rotation of the warp beam is controlled by mechanism connected to the whip roll and other mechanism governed in accordance with the variation in diameter of the warp supply on the warp beam. Even when a vibrating whip roll is used, momentary increases or decreases in tension of the warp sheet may occur because of operation of the harness frames, improper operation of the let-off mechanism or for other reasons. Such variations in warp tension result in variations in cloth structure and appearance and consequently in lower quality of the cloth produced.

One object of the present invention, accordingly, is to provide an improved let-off mechanism for a loom wherein the warp sheet is maintained under substantially uniform tension dur ing operation of the loom. To this end and in accordance with one feature of the invention, the loom is provided with a let-off mechanism which is arranged to oscillate the warp beam in response to increases and decreases in warp tension thus compensating for such variations and providing substantially uniform tension on the warp sheet at all times.

A further object is to improve generally upon the operation and construction of looms.

I With the above and other objects and features in view, the invention will now be described with particular reference to the accompanying drawings which illustrate a preferred embodiment of the invention and in which:

Fig. 1 is a View in side elevation of a portion of a loom having the invention thereto applied.

Fig. 2 is a view in rear elevation of structure shown in Fig. 1;

Fig. 3 is an enlarged detail view of a portion of the let-off;

Fig. 4 is a sectional view taken along the line 44 of Fig. l, the scale of Fig. 4 being somewhat greater;

Fig. 5 is a view of certain of the parts shown 2 Fig. 1, as viewed from above in that figure, on a. reduced scale; 7 Fig. 6 is a, sectional view taken along line 6--6 of Fig. 2, with parts omitted for the sake of clarity; and

Fig. 7 is a sectional view taken along line 1----'[ of Fig. 2, with certain parts omitted in the interest of clarity of illustration.

The present drawings show only a portion'o the loom with the improved let-off mechanism applied thereto. The parts of the loom which are not shown are of usual construction and form no part of the present invention. The present invention is illustrated as applied to a positive type of let-off mechanism which includes a warp beam geared to a transmitting shaft which is driven from suitable mechanism connected with the operating structure of the loom. The let-off mechanism to which the .in'-, vention is shown applied in the illustrations is of the well known Ropertype such as is illustrated in general form in Patents Nos. 647,815 to Draper et al.; 731,622 to Roper; 1,704,911 to Burnham, and 1,758,738 to Draper, but the invention is equally well adapted for employment in othe types of let-off mechanisms.

The drawings show the rear right hand side of a loom which includes a side frame Ill having a suitable bearing l2 in which the right hand end of a shaft Hlis journaled. The shaft [4 supports a warp beam 16 holding a warp supply. A sheet of warp threads, I8, commonly called a warp sheet, extends from the beam to the weaving mechanisms of the loom. The warp beam I6 is arranged to be positively driven through a gear 84, preferably formed integrally with one head of the beam, meshing with a driving pinion 82 (Fig. 4). Driving pinion B2 is affixed to and rotated by a shaft 42 mounted for rotation in bearing means 42a mounted on a bracket Illa secured to the loom frame in any desired manner. At its opposite end shaft 42 carries affixed thereto a pawl wheel I'll carrying a pawl H2. Pawl I I2 is spring pressed by a spring I I3 into engagement with teeth H4 formed on a side face of a gear 18 mounted forfree rotation on shaft 42. Gear 18 has a flange carrying internal gear teeth 18a. Referring'to Fig. 6, gear '18 is arranged to be rotated by a planetary ring gear 16 which is rotatably carried in anorbit around shaft 42 by an eccentric 14 on which the ring gear is slidably mounted. Ring gear- 16 is restrained from free rotation about its own axis by laterally extending lugs 16a integral therewith which slidably ride in slots 16b formed in a generally T-shaped member 80. Member is, withan exception to be fully explained hereinafter, restricted to reciprocatory motion in a direction at right angles with a line interconnecting lugs 16a, with hub, [20. sliding in a cut-out 800. formed in mem ber 80'.

Referring to Fig. 4, eccentric i4 is seen to be mounted for free rotation on shaft 42 and to have integrally formed therewith a sleeve hub portion 12a and a ratchet wheel l2 carrying ratchet teeth 12b on its periphery and a friction flange 720. The previously mentioned centrally located cut-out or guideway 8% (Fig. formed in member 86 closely engages thehub portion 12a of eccentric 14 with a sliding fit.

Referring to Figures 1, 4 and "I, thereis mounted for rocking movement on shait 42 apawl carry: ing lever 40 carrying at its upper end a pawl 70 which overlies and engages the teeth of ratchet wheel 12. Lever 40 has pivoted thereto at its lower end a rod 44 which at its forward end carries a slotted member 46. Mounted rigor tree. r. tation on 'azshaf-t 54 .suppfl ftgdyby bracket bearingmeans afiixed -t o .thelooznside is bell cranl; lever 52 having a pin 50 riding in the slotdb of memberj ifi. At the end f: the other arm at of lever '52 there ispivotal v .0. 351. a d d 58. Refer in to Fia Lit. wi be S en ha he draw'rodcarriesat its for-ward end a slotted head 58a in the slot of which rides a draft bracket 60w mountedon' a lay-swordififl.

As thelay sword oscillates forwardly and back. in the loom, bracket v5.0a :will; cyclically first posh tively draw head Bdrrand "rod 58 forwardly to afixed position,'andthenallowrod 58 to be moved rearwardly. As rod .58 is drawn forwardly, lever 52 is rocked, moving pin Sbtothe lower end of slot 48 and then drawing rod -44 forwardly (to the left in the drawings) In-turn, rod '44; rocks lever 40, causing pawl "l t; to rotate ratchet wheel I2; and eccentric l4. overthrow, and -retrogressive rotation of ratchet wheel (2 are prevented by fricthe rin gear will as it moves through itscrbit,

rotate gear 18, with whose teeth it engages. Gear Hi is thus rotated inisma'llsteps, .at a lowerrate *of revolution than that of'ratchetwvheel l -2,. 'XVith pawl l [-2 in engagementwitha tooth 1-H; ongear "I8, pawl wheel HI will becrotated in unison with gear 18, and will in turn rotate shaft 42. andpinion Thus warp beam I 6 will be slowly rotated in a direction to let oif warp l8.

Reference to Figs. 1 and .'7 will show that While the lay sword causes a positive driving movement 'of rod 58, lever 52, rod 44 and lever 40 each to a prescribed position at each forwardmovement of the sword, the non-driving or return movement of these parts is not positive due to the :lostmotion connections at slotted head 58d and at -slot'48. movement of le-ver' ifl the average rate of rotation Hence by governingthe extent of return of the ratchet wheel 12, and hence of beam 16, can be regulated. This regulation oiithe rateof rotation isefiected in accordance with two factors, namely, the tension of the warp sheet extending from the warp beam and the diameter of the warp mass on the beam l6. These two regulating functions and the means for effecting them will now beexplained.

Referring to Figs. 1 and 5, it will be noted that the warp sheet [8 extending from the warp mass on beam l6 passes upwardly and over a whip roll iii. The whip roll is journaled on arms 22 having shaft-like extensions 25 resting in saddle bearings or seats in arms 23 secured on a transverse shaft 245 extending across the loom beneath the warp sheet. Shaft 2G is journaled in saddle bearings in brackets 26 affixed to the loomsides. Only those'of members 22, 23, and'26 at the right hand side of the loom are shown, it being understood that similar complementary members are provided at the opposite side of the loom. An arm '53 is fixed on extension 25 at the right hand loomsi'de, and rests on a bracket ll affixed to the 100.315.15 8 IQ, to limit rotation of arms 22 and the whip roll about the axis of extensions 25 under the force of the warp sheet on whip roll fill. Shaft 24 has afilxed thereon at the right hand loomside adenending arm 28. Referring to Figs. 1 and '7, it will be noted that arm 28 has pivotally attached thereto at it lower end a rod 3i]. rod is pro: vided with a collar, j-preierably of two-piece .adjustab-le construction. Adfiustably affixed to the loognside i0 is a bracket't having an abutment 34 having a guide hole through which rod 50.1.5; arranged to slide. On rod 30 and between abutment 3d, and collar '32 thereisprovided a compression pring 36. This spring tends to maintain the rod 30, arm 28 and arms 23 in position with h 511 2-8 p es d tightl aga ns h warp sheet, but allowing the whip r011 tomove in roe sponse to variations in tension in the warp sheet. Pivotally mounted as ona pivot'39a on bracket 39 is a depending lever -38carrying a pivot pin 38a on which is journaled the lower end of rod 38,. Beter-ri-ng to Figs. .4 and '7 it .may be seen that levers 38 and 419 are provided with opposed channeled lever arms the channels of which is arranged an adjustable transmitter 68. This trans.- mitter is arranged to be vertically positioned by means described hereinafter, and is effective, in any of its several positions, to transmit forces from either of .the levers to the other. Thus at each forward beat of the lay sword lever 40 is rocked clockwise to a prescribed position, and lever 38 is, through the transmitter 68, rocked counterclockwise. As the lay sword moves rearwardly and allows the linkage connected thereto to partake of return movement, the extent to which pawl carrying lever 40 is returned is governed first by the extent to which the warp sheet tension causes lever 36 to return under the counteracting pressure exerted by spring 36, and secondly by the vertical position of transmitter 68 in the channels of the two levers. It is evident that the lower transmitter 58 is in the channels, the greater is the resultant return movement of lever 46 for a given extent of retu rn movement of lever 38.

From the above it isnseen that the return movement of pawl carrying lever 30 is regulated by the tension in the warp sheet, being greater in response to increase in warp tension and less in response to decrease in warp tension.

Since the warp mass on warp beam 15 decreases in diameter as the warp is used, means for increasingthe rate of rotation in accordance with the decreasing diameter of the warp mass must be provided. The structure provided for this purpose comprises an arm 62 secured on the inner end of shaft 54 and having a shoe or runner bearing against the warp mass on the beam. As the runner follows the surface of the warp mass inwardly as the diameter ofthe latter decreases, shaft 54 is slowly rotated. This slow rotation is imparted to an arm 64 secured at one end to the shaft near its outer extremity. At its other end arm 64 is pivotally connected to a bar 66 carrying at its upper end the aforementioned 4 transmitter 68.- It thus is seen that the vertical position of transmitter 68 in the opposed channels of levers 38 and 48 is governed in accordance with the diameter of the remaining warp mass on beam 16; and that as the diameter decreases transmitter 68 is slowly lowered to cause a gradual increase in the extent of the nonworking or return strokes of pawl carrying lever 48.- Thus the rate of rotation of the warp beam is slowly increased to compensate for gradual decrease in diameter of the warp mass.

'The structure hereinabove described operates to regulate the rate of rotation of the warp beam in accordance with the tension in the warp sheet and in accordance with the decrease in diameter of the warp mass, and may be of the type and construction commercially employed on many looms.

Relatively large variations in the tension in the warp sheet occur during each weaving cycle, such variations being caused by the reed beating up the weft yarn, and by the action of the harness motion in sheddin the warp threads. The maximum tension produced may be sufiicient to cause parting of many of the warp threads if not relieved. The structure provided by the present invention is directed toward the relief of increases in warp sheet tension; and as shown in a preferred embodiment of the invention illustrated in the drawings, relieves the cyclical ten- ,sioning of the warp sheet by allowing the warp beam to oscillate about its axis.

. In prior constructions of the let-off previously described, the slot in the lower end of member 88 was fitted over the end of shaft 54, allowing .member 88 to reciprocate in a diagonal direction with shaft 54 riding in the slot and restraining member 88 from rotation. According to the invention, member 88 is permitted to oscillate in response to the variations in torque applied to it from the warp sheet through pinion 82, shaft 42, pawl wheel Ill, gear 18 and ring gear 16 whose lugs 76a, engage in slots 16b of member 88, Re-

ferring to Figs. 1 and 3, a shaft 86 is slidably mounted in holes formed respectively in a bracket 88 and an arm 98. Bracket 98 is secured as by bolt means 94 to an outboard bearing bracket 92 affixed to the loom frame, and acts as a fixed "nut, as shown in Fig. 4. The connection thus made between shaft 86 and member 88 is relatively loose so that bolt 88 may slide freely in the slot and not cause shaft 86 to be raised or lowered as member 88 rises and falls in the normal course of its movements. A collar 96 is fixed on shaft 86 to prevent excessive movement of the shaft rearwardly in the guides. A second collar I82 is fixed on the shaft and serves as an abutment against which a compression spring I84 bears. The other end of this spring presses against arm 98.

6 As hereinabove indicated, the tension in the warp sheet produces a torque on the warp beam, which torque is transmitted to ring gear 18. That gear tends to rotate member 88 about shaft 42 in a counterclockwise direction as viewed in Fig. 6 of the drawings, with a degree of torque proportional to the tension in the warp sheet. In let-off mechanisms prior to the present invention the torque applied to member 88 was countered by forces acting on member 88 by shaft 54, which rode in the slot in the lower end of the member. Member 88 did not yield under excessive warp sheet tension, with the result that a yieldin whip roll was necessary with the prior constructions above mentioned. According to the present invention, member 88 moves as soon as torque is applied by the ring gear, rotating clockwise and compressing spring I84 until the back pressure exerted by the spring balances that produced on bolt 88 by the mentioned torque on member 88. Thus variations in tension in the warp sheet during the weaving cycle are transmitted to member 88, which oscillates about shaft 42 as an axis in response to the variations in warp sheet tension. As member 88 oscillates, ring gear 16 and the other gearing connecting the ring gear with the warp beam l6 also oscillates; and the warp beam oscillates accordingly, relieving the increases in warp sheet tension and absorbing decreases .in that tension. Since the torque arm measured by the distance between shaft 42 and bolt 88 is not varied as member 88 is raised and lowered in response to orbital movement of ring gear 18, the counter-torque applied to member 88 by spring I84 is constant for any particular degree of compression of the spring; and the oscillations of member 88 will accordingly be generally uniform over a long period of time.

As the warp sheet is unwound from the beam l6 and the diameter of the remaining warp mass decreases, the torque applied to the gearing by the warp sheet tension will decrease, owing to the decreasing effective length of the lever arm to which the tensile forces are applied. As a result of this gradual decrease in torque, member 88, Fig. 3, would gradually move counterclockwise about shaft 42 in its oscillations. This movement is obviated by a gradual relieving of spring 184 by the gradual clockwise rotation of arm 98 as beam follower 62 maintains contact with the decreasing warp-mass on the beam. Hence member BB-may remain in a generally vertical position as it partakes of its relatively rapid oscillatory movements and its slower rise and fall movements.

From the above it will be seen that the invention provides means whereby the warp sheet may be positively let off from the warp beam at a closely regulated rate, and the tension thereof held closely to a fixed desired value throughout the feeding of an entire beam of warp, and whereby the warp sheet tension is maintained substantially constant throughout the weaving cycle of the loom.

'' Having disclosed a preferred embodiment of the invention it will be evident that changes and modifications thereof will occur to those skilled 'in the art, and what I claim and desire to secure by Letters Patent of the United States is:

1. In a warp let-off mechanism for a loom having a warp beam from which extends a warp sheet subject to repeated variations in tension, in combination therewith: forwardly and reversely operable means including a shaft and gearing carried by the shaft and arranged for rotation in a animus-1 eiorward direction to permit forward rotation of the'b'eamto let off warp from the 'beamand arranged for rotation in the reverse direction to reversely rotate said beam to wind warp thereon, :saidgearing including afirst gear rotatable about the shaft axis and a planetary gear in engagement with' 'said first gear power means acting to impart planetary motion *to said planetary gear; an oscill'atable member straddling said shaft and engaging andrestricting rotation of said planetary gear about its own axis to cause the planetary gear to drive'said first gear incident to action of said power means, said member :in turn having torque imparted thereto by said planetary gear, and'me'ans engaging said member and including a spring arranged to be stressed by movement of said member in one direction caused by increase in tor ue applied to said member upon forward rotation of said gearing and beam incident 'to increase in warp sheet tension, said springarranged "and acting to oppositely move said member and reverselyrrotate said gearing and beam upenderease in saidtorque incident todecrease in warp sheet tension, whereby said warp beam is oscillated in responserto said repeated variations in warp sheettension to reduce the magnitude of said variations.

2. In a warp let-off mechanism for a 1001 "having-a warp beam subjected to a fluctuating torque by a warp sheet whose tension fluctuates; .30

from rotation about its own axis, said yieldable;

means including a resilient member arranged to "yield in response to increase in said transmitted torque incident to increase in warp sheet tension and to return in response to subsequent decrease in said transmitted torque incident to decrease in warp sheet tension; whereby said warp beam is oscillated in response to said fluctuating warp sheet tension to reduce the magnitude of the fluctuations.

3. In a loom having a warp beam and a warp sheet being drawn therefrom under tension, means for rotating said beam to let off warp therefrom which includes intermeshing gears and a ratchet wheel and pawl and means for actuating said pawl for intermittently advancing said gearing, and means for controlling the rotationof the warp beam as advanced by said pawl and ratchet wheel to relieve excessive tension in the warp sheet and to increase tension therein when the 'warp tends to become too slack, said means func-- tioning through said intermeshing gears and comprising an arm attached at one end for movement with one of said gears and an anchor means for the opposite end of said arm comprising a resilient means by which the arm is restrained to 'osciilate under forces imparted through said gears within a predetermined angular extent.

4. In a loom having a warp beam and a warp sheet being drawn therefrom under tension, means for rotating said beam to let off warp therefrom which includes intermeshinggears one of which is a planetary gear, and a ratchet wheel and pawl and means for actuating said pawl for intermittently advancing said gearing,-and other .--eneans. for controlling'the rotation of the warpbeam-as advanced by saidzpawlland ratchet wheel to relieve excessive tension in the warp-sheetand to increase tensiontherein when the warp tends to become. too slack, said means functioning through said intermeshing gears and comprising an arm attached at one end for-movement-with said planetary gear and an anchor means to whichthe opposite endor the arm is connected,

asaid' anchor meanscomprising a resilient means by which the arm: is restrained to oscillate under forces imparted through said gears within a predetermined angular extent.

5. Inra loom having a warp beam and a warp sheet "being drawn therefrom under tension, means for rotating said beam to let off warp therefrom which includes a plurality of intermeshing gears one of whichis a planetary gear, and a ratchet wheel and pawl and meansfor actuating said pawl for intermittently advancing said gear-ing comprising connections to the pawl from the reciprocating la mechanism of. the loom, and other means for controlling the Irotation of the said warp beam as advanced by said pawland ratchet wheel to relieve excessive tension in the warp sheet and to increase tension therein when the'warp'tends to become too slack, said controlling means functioningthrough said inter'meshing gears and comprising an arm having one end thereof formed as a crosshead and means between said'planetary gear and crosshead for preventing relative rotation between thetwo, and an anchor means to which the opposite end of thesaid arm is connected, said anchor means comprising a resilient connection and stop means, said resilient connection and stop means being so devised as to limit the extreme angular oscillation of the arm and planetary gearand for resiliently limiting that oscillation within a predetermined angular extent. i

'6. For a let-off for a loom having a warp beam and a warp sheet drawn from said beam under tension, said let-oil? comprising a train of gears one of'whichisa planetary gear and pawl and ratchet-means for advancing said train of gears, a means for preventing relative rotation. of said ,planetary gear beyond a relatively small angular extent and. for relieving excessive tension in the warp sheet and increasing tension therein when the warp tends'to become too slack, comprising an arm and means between said planetary gear --and.arm for preventing relative rotation between :the two, and an anchor means for the opposite end of said arm comprisinga resilient connection thereto for restraining the oscillation of the arm within a relatively small angular extent.

7 For a let-oif fora loom having a warp beam and a warpsheet drawn from said beam under tension, .said let-off. comprising a train of gears one of which is a planetary gear and pawl and ratchet means for advancing said train of gears,

,a-means for preventing relative rotation of said planetary gear beyond a relatively small angular extent and for relieving excessive tension inthe warp sheet and increasing tension therein when the warp tends to become too slack, comprising an arm having at one enda cross head, inter- .engaging means between the planetary gearand the crosshead for preventing relative rotation between thegear and arm, and an anchor means for the-opposite end of said-arm which comprises I a rod member, a connection between the arm and rod member, stop means for limiting movement-of the rod inone'direction and resilient means for restraining the rod and the arm thereby toprevent movement of the arm and planetary gear Number beyond a relatively small angular oscillation 731,622 therefor. 744,941 WALLACE HAMILTON. 1,704,911 5 1,758,738 REFERENCES CITED 1 7 1 11 The following references are of record. in the 1,365,119 file of this patent: 2,092,718 UNITED STATES PATENTS 10 2350354 Number Name Date 647,815 Draper Apr. 17,1900

10 Name Date Roper June 23, 1903 Roper Nov. 24, 1903 Burnham Mar. 12, 1929 Draper May 13, 1930 Burdett June 3, 1930 Lindsjo June 28, 1932 Lundgren Sept. 7, 1937 Brown June 6, 1944 

